These women in the early years of the 20th century maintained and analysed early images of the stars recorded on delicate glass negative plates under the direction of then-director of the Harvard College Observatory Edward Pickering.

One of the astronomers, Williamina Fleming, began work as Pickering’s maid but went on to identify hundreds of stars, while Henrietta Swan Leavitt’s observations about the luminosity of stars would shape later ideas about the expanding universe.